The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
(1) Field of the Invention
This invention generally relates to a system for sensing the speed and time-position history of an underwater projectile, over the entire length of a run, for the Adaptable High Speed Underwater Munition (AHSUM) project. More particularly, the invention relates to a sensing circuit for providing a state output of a plurality of sensors used in the testing of an underwater projectile. The state output is used to determine a position and speed of the projectile during an entire run thereof through the plurality of screens.
(2) Description of the Prior Art
The known Adaptable High Speed Underwater Munition(AHSUM) project needed to record the speed and position of the projectile over the entire length of the underwater firing range. This provides valuable acceleration and deceleration data during the course of the test. Due to data acquisition channel limitations and a large number of sensors, a method was required to provide the speed and position data for the entire run over a single channel.
Thus, a problem exists in the art whereby there is a need for a sensing device which is able to sense both the speed and time position history of an underwater projectile over the entire length of a test range.
The following patents, for example, disclose various types of devices for determining projectile position and velocity, but do not disclose a device for sensing projectile velocity or time-position history using a sensing circuit according to the aspects of the present invention.
U.S. Pat. No. 4,147,055 to Wood et al.; and
U.S. Pat. No. 5,210,488 to McKeag.
Specifically, the patent to Wood et al. discloses an apparatus for measurement and correlation of chamber pressure and projectile position. The data is accomplished using an array of photo transistors, illuminated by collimated light, which photo transistors are sequentially switched off due to the interruption of the collimated light by the passing projectile. Pulses generated thereby may be displayed on an oscilloscope along with the pressure-time trace.
The patent to McKeag discloses a velocity measurement system for determining velocity of a launched projectile in a launch tube in an underwater environment. The system includes a transformer with secondary coils arranged in discrete groups with an increment of insulation shielding each of the groups of coils from the water therearound, the insulation increments being connectable to the projectile and being successively separable from the groups of secondary coils to expose such groups of coils successively to the water to short out such coils and reduce the voltage of the transformer secondary, and means for converting the speed of voltage reduction to the velocity of the projectile in the tube. In the case of launch of the projectile from a submarine, at least preprocessing of the voltage of the secondary is performed in the launch tube, and the pre-processed signal is passed to within the pressure hull of the submarine via a sealed electrical connector in the breech door of the launch tube to provide sub-safe conditions.
It should be understood that the present invention would in fact enhance the functionality of the above patents by providing a simplified device for sensing projectile velocity in an underwater environment.
Therefore it is an object of this invention to provide a device for sensing projectile velocity.
Another object of this invention is to provide a device for sensing projectile time-position history along with velocity in an underwater environment.
A still further object of the invention is to provide circuitry which is an accurate and inexpensive method to measure the velocity and time-position history of a projectile under the water.
Yet another object of this invention is to provide a device for sensing projectile velocity and time-position history in an underwater environment which is simple to manufacture and easy to use.
In accordance with one aspect of this invention, there is provided a system for sensing projectile velocity and position having a plurality of support members positioned in a path of said projectile. Each support member has an aperture with a resistive trace supported in the aperture. The resistive trace can be separated by the projectile""s passage. A sensing circuit is joined to each resistive trace and provides a signal indicating separation of the resistive trace. This signal is provided to a logic circuit which provides a single signal indicating separation of each said resistive trace. A data acquisition system provides an output indicating said projectile velocity and position with respect to time.